The Water Footprint of Hydropower Production—State of the Art and Methodological Challenges

Abstract

energy production, which has boosted large-scale investments in solar, wind, and hydropower. [5] There is a growing understanding of the close relation between water and energy, sometimes entitled the waterenergy nexus. [6][7][8][9][10] Water is highly needed in the development of energy resources, and access to energy is a prerequisite in the provision of water services. According to ref.[10], primary energy production and power generation accounted for roughly 10% of total worldwide water withdrawals and around 3% of total water consumption in 2014, which corresponds to withdrawals of around 400 billion m 3 annually. Several regions now experience water stress, [11] and access to water might constrain the further development of energy sources.Production of hydropower is exclusively dependent on the availability of the local water resources, and reduction in the available water will immediately reduce the power production. Among the world's 45 000 registered large dams and reservoirs, [12] ≈75% are classified as single purpose, meaning that they are used exclusively for one specific purpose. [13] The most common single purpose is irrigation (47%), followed by hydropower (19%), water supply (11%), flood control (9%), and the remaining recreation, navigation, and "unclassified." Among the multipurpose reservoirs, serving two or more functions, which is ≈25% of the registered dams, irrigation is also the most frequent purpose. 61% of the registered multipurpose reservoirs have irrigation as one of several functions, followed by flood control (50%), water supply (44%), hydropower production (40%), recreation (30%), and navigation (6%).The world's reservoirs are expected to play an even more important role for the society in the future. Climate change might reduce the available water in arid areas of the world, increase the runoff in wet areas, and change the seasonality. Large developments of intermittent power sources, such as wind and solar power, can also increase the need for flexible energy production, [10] served by for instance by hydropower with reservoirs. [14] This paper aims at:1. Reviewing published estimates of water consumption from hydropower production. 2. Presenting the methodology applied, identify shortcomings and propose improvements.

The Global Food‐Energy‐Water Nexus

“…Most of the water stored is returned to the environment. The major contributor to water consumption in hydropower plant is evaporative loss from the reservoir (Bakken et al, 2017). Such losses are site specific and vary with reservoir size and climate and are minimal in the case of flowing water systems with no reservoirs (Bakken et al, 2013;Scherer & Pfister, 2016).…”

The water footprint from hydroelectricity: a case study for a hydropower plant in Romania

“…where WEtr is evapotranspiration of the flooded area, [m 3 /y], that is the quantity of water evaporated before the existence of the dam. Many authors consider it more appropriate for the calculation of the real water consumption by hydropower, [20][21][22][34][35][36].…”

The Innovative Gaildorf Wind-Water Project Guarantees Reliability of Power Supply

“…During analysis of operation of the hydroelectric power plant, the evapotranspiration of water, which covers the process of volatilisation of the water into the atmosphere through plant transpiration and sublimation, was taken into account [30,31].…”